Temperature regulation



June 25, 1929.

L. K. MARSHALL TEMPERATURE REGULATION Filed Nov. 22, 1925 Patented June 25, 1 929.

UNITED STATES PATENT OFFICE.

LA URENCE K. MARSHALL, OF WEST SOMERVILLE, MASSACHUSETTS, ASSIGNOR TO SPENCER THEBMOSTAT CQ, OF CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

TEMPERATURE REGULATION.

Application filede November 22, 1923. SeriaLNo. 676,300.

Heretofore it has been common practice.

to accurately adjust temperature responsive devices such as thermostats in order to renderrthem relatively sensitive to small changes of temperature. However, when constructed V for such'adjustment they are,unsuitable for performing operations requiring appreciable physical displacement or expenditure of energy, owing to the relatively small movement taking place and the small amount of energy available in temperature responsive devices when small temperature changes occur. The minuteness of the maximum physical movement taking place within a delicately adjusted responsivedevice such as a thermostat limits the capacity of the device posi tively to actuate apparatus" Delicate adjustment is further objectionable on account of the consequent unreliability of operation of the device, inasmuch as very slight changes in the conditions of the device or of the apparatus operated thereby destroy the initial delicate adjustment.

On the other hand if the temperature re sponsive device he made relatively large and rugged and be given a coarse adjustment so that a relatively large physical movement occurs when the device'operates, the upper temperature at which the device operates relatively remote from the lower temperature at which it operates, and the device is accordingly unsuitable to respond directly to changes temperature with the proper degree of sensitivity.f'"-j Many kinds of apparatus, such as electrical switches for example, require relatively large physical displacement of theparts such as contacts, particularly '-in the case of switches when large quantities of electric energy are to be controlled. While the physical displacement taking place in a delicately adjusted thermostat-maybe mechanically amplified to a'certain extent, the frictional losses and other difiiculties limit the extent to which this expedient can be satis factoril carried, the limit being considerably be ow that required for the operation of electrical contacts to interrupt relatively large amounts of power.- Even when a plurality of'contacts are arranged to operate in series to increase the total gap-in the circontacts cuit, the advantage gained is limited and is temperature within which the temperature responsive device should operate. A deli- .cately' adjusted thermostat is therefore uniuitable for directly operating such appara- Objects of the. present invention are to overcome the above difficulties, to provide an improved method of operating temperature responsive and temperature regulating apparatus to provide temperatureresponsive apparatus of simple'construction capable of positively producmga large abrupt response to a predetermined small change of temperature and adapted to operate electrical to interrupt relatively large amounts of power without arcing, and generally to provide vtemperature responsive and temperature regulating apparatus of improved form and improved operating characteristics.

Ina-ccordance with the present invention a temperature responsive, device havin a g ven sensitivity is controlled byanot er more sensitive temperature responsive device which controls the operation of the first device by effecting a change in its temperature. In another aspect the invention contemplates regulating the temperature of a body or medium by a temperature responsive device the temperature of which is in part at least controlled bya second device responsive to temperature changes in the body or medium.

' The invention will now be described, in connection with a specific embodiment with particular reference to the accompanying drawings, in which:

Fig.1 is adiagrammatic elevation partly in section of an embodiment of the invention; Fig.2 is a plan of 'Fig. l; and; 3

Fig. 3'i s an enlarged vertical section of a portion of the apparatus takeimalong the line' 3-3 of Fig; 2. y

In Fig. 1, .a source of electric energy 10' supplies; current .to the heating resistance element 11 for the boiler 12. The control .device 13 is positioned in heat transfer relathermostat 14 comprising an elastic bimet'alsmaller and more sensitive than thermostat lic disc, having the form of a shollow cup, 14 inasmuch as the power transmitted to is fixed in position at its center and has a resistance 18 may be relatively small as comfree edge which abruptly engages contacts pared to that transmitted to resistance 11. 15 to close the circuit between source and Thermostat16 in conjunction with resistance resistance 11 when the temperature in de- 18 and source 10 amplifies the effect of excreasing reaches a predetermined'low value, cessive .heat in boiler 12 and transmits the the patent to Spencer No. 1,448,240, although creased above 70 F.

and abruptly opens the contacts to interrupt amplified heat to thermostat 14.

the transmission of power from the source In case the body 12 were a room within 10 to resistance 11 when the temperature in which the air was to be maintained between increasing reaches a predetermined high the temperatures of 65 F. and 70 F., the

value, the thermostat being of the quick or sensitive thermostat 16 could be adjusted to snap action type more fully disclosed in close contacts 17 when the temperature inand to open the contacts any other suitable form of thermostat may again when the temperature decreased below be employed. Thermostat 14 may be rela- 65 F., whereas thermostat 14 could be tively large and rugged in construction and roughly adjusted to operate at much more adjusted abruptly to produce a wide separation between the disc and the contacts when the thermostat operates in response to an widely separate temperatures as, for example, to open contacts 15 at 90 F. and to close the contacts again at 65 F. In this way excessive temperature. relatively large amounts of power could be An auxiliary thermostat 16 is housedwithcontrolled to maintain the air at a temperain control chamber 13 adjacent boiler 12, and ture between 65 and 70. responds to a predetermined increasing te'm- Many other applications of the invention perature less than that of thermostat 14 to are obvious, the principle of producing an close contacts L17 and connect .a relatively amplified response to a very limited tempersmall heating resistance 18 in shunt to a ature change and of regulating large portion of resistance 11 so that current from amounts of power to maintain the temperathe source 10 passes through resistance 18 ture of a body within a narrow temperture when contacts 15 are closed and rapidly range or between two temperatures relaheats thermostat 14. Chamber 13, housing tively near to each other on the temperature elements 14, 16, and 18, unites these elements scale, being of broad application. in a unitary structure. I claim:

For example, if the upper operating tem- 1. In a heating system, heating means, temperature of thermostat 14 be 500 (1., and perature responsive means for controlling the lower or cold operating temperature be said heating means, and separate tempera- 300 0., While the -upper opreating temperture responsive means in heat transfer rel'aature of thermostat 16 is, say, 325 0., and tion to said heating means for separately the lower operating temperature is 300 C., it will be seen that as long as power is being delivered to resistance 11 to maintain boiler 12 between 300 C. and 325 'C., thermostat 14 will tend to maintain contacts 15 closed and thermostat 16 will tend to maintain conremote from boiler 12, produces no appreciable, change in the temperature of the boiler, but is sufficient to heat thermostat 14 and in effect indirectly to render the thermostat responsive to vary much smaller changes in the temperature of the boiler than could directly cause the actuation of the thermostat. Thermostat 16 may be controlling the operation of said first temperature responsive means, said first and second mentioned temperature responsive means being subjected to substantially like temperature variations, and said temperature responsive means having different operating ranges, and controlling different amounts of energy.

2. In a heating system, heating means, temperature responsive means for controlling said heating means, and physically separate temperature responsive means in heat transfer relation to said heating nieans for separately controlling the operation of said first temperature responsive means, said separate responsive means being more sensitive to changes of temperature than said first responsive means, and subjected to substantially like temperature changes, and controling different amounts of energy.

3. In a heating system, a body to be heated, means to heat said body, means responsive to changes in the temperature of said body for controlling the heat supplied thereto and determining the minimum temperature thereof. separate heating means i" or heating said responsive means, and responsive means physically separate from said first responresponse to changes in the temperature of 7 said body, said separate responsive means ture changes,

being more. sensitive to changes of temperature than said first named responsive means, and subjected to substantially like temperaand controlling difierent amounts of energy. Y a

5. In a heating system, a body to be heated, an electrical heating element to heat said body, means responsive to changes-in the temperature of said body for controllingthe heat supplied thereto by said heating element and determining one temperature limit thereof, a separate heating-element for heating said responsive means, and separate responsive means for controllling said separate heating element independently of said first heating means in response to changes in the temperature of said body, said tempera ture responsive means cont-rolling difierent amounts of energy.

6. In a heating system, a body to be heated, means to heat-said body, a thermostat responsive to changes in the temperature of said body for controlling the heat supplied thereto, separate heating means for heating said thermostat, and a. separate thermostat for controlling said separate heating means independently of said first heating means in response to changes-in the temperature of said body, said thermostat being subjected to substantially like temperature changes andcontrolling difierent amounts of energy.

7 In a heating system, a body to be heated, means responsive to a predetermined decreasing temperature of said body to' causeheat to be supplied to said body, separate means responsive to a predetermined increasing temperature for causing heat to be supplied to sand first means, said first means being responsive to heat from said so aratev meansfor discontinuing the supply 0 heat to sald body, said temperature responsive I means controlling different amounts of en'- I for connecting said source to said resistance,

a separate heating resistance for said responsive means, and separate means for connecting said source to said separate resistance to heat said first responsive means to cause it' to disconnect said source, from said first heating resistance, said temp: ature responsive means and separate tinnecting means controlling different amounts of en- 9. In apparatus of the character desciibed, temperature responsive means, and separate means responsive to temperature changes of smaller rangethan said first means for separately causing said first means to abruptly operate, said means both being subjected to like temperature ranges.

l0.- In apparatus of the character described, temperature responsive means having predetermined operating temperatures, means adjacent said responsive means to vary the temperature thereof, and separate temperature responsive means having predetermined operating temperatures nearer togetheron the temperature scale than those of said first mentioned responsive means for separately controlling said temperature varying means, said two temperature responsive means being subjected to substantially the same temperature variations, and

when the adjacent temperature passes a predetermined value in the same direction. 12. The method of actuating a thermostat having appreciably difi'erent predetermined hot and cold actuating temperatures which comprises abruptly applyingheat to Stud: thermostat when the temperature. in r1s1ng exceeds said cold value and reaches a value appreciably less than said hot value.

13. In apparatus of the character described, temperature responsive means abruptly" operating at relatively widely spaced temperatures, andsepara-te means responsive to temperature changes of smaller range than said first means for separately causing. said first means to abruptly operate said temperature ranges coinciding atone end thereof.

14. In apparatus of temperaturechangesof smaller range than said first means for separately causing said first means to abruptly operate when said body is at a temperature nearer said temperature limit than the difference between said widely spaced temperatures, said temperature ranges coinciding atone end thereof.

15. A heat transfer regulator for regulatthe character described, a body tobe heated, temperature ing the temperature of a body comprising a thermostatic heat transfer controller for controlling the temperature of said body, auxiliary heat transfer means associated with, said thermostatic controller; for controlling its temperature, and an auxiliary thermostat responsive to the temperature of said body for regulating said auxiliary heat transfer means independent-l of thefmain thermostat, said auxiliary thermostat and thermostatic controller having different temperature ranges and controlling different amounts of energy.

16. A heat transfer regulator for regulating the temperature of a body comprisin a thermostatic heat transfer controller for controlling the temperature of said body, auxilia heat transfer means associated with said thermostatic controller for controlling its temperature, and an auxiliary thermostat responsive to the temperature of said body for regulating said auxiliary heattransfer' means independently of the main thermostat, said auxiliary thermostathaving a shorter temperature range than the thermostatic controller and controlling different amounts of energy.

17. A heat transferregulator for regulating the temperature of a body comprising a thermostatic heat transfer controller for controlling the temperature of said body, auxiliary heat transfer means associated with said thermostatic controller for controlling its temperature, and an auxiliary thermostat responsive to the temperature of said body for regulating said auxiliary heat transfermeans independently of the main-thermostat,

said auxiliary thermostat tending in a dimotion to increase the temperature of the thermostatic controller while the thermostatic controller is tending in a direction to decrease the temperature of said body, said.

thermostats controlling different amounts of energy.

' 18 A heat transfer regulator for regulating the temperature of a body comprising a thermostaticheat transfer controller for controlling the temperature 'of said body, auxiliary heat transfer means associated with said thermostatic controller for ontrolling its temperature, and an auxiliary thermostat responsive to the temperature of said body for regulating said auxiliary heat transfer means independently of the main thermostat, said auxiliary thermostat functioning to control .said auxiliary heat transfer means at onetime and said thermostatic controllerfunctioning to control the tem erature ofsaid bodyat .a later time, said thermostats controlling different amounts of ener y.

iii). A heat transfer regulator for regulating the temperature of a body comprising two thermostats constructed to move to open and closed positions at predetermined. tem-.

temperatures respectively, an

peratures respectively, and means res on sive to one thermostat while the other t iermostat -is stationary for afiectingthe other thermostat one thermostat tending toward one of said positions during an interval when the other thermostat is tending toward the opposite of said positions.

20. A heat transfer 're ulator for regulating the temperatureof a body compris ing two thermostats constructed to move to open and closed positions at redetermined a. heater responsive to one thermostat independently of the other thermostat for heatin the other thermostat, one thermostat tendm to close during a period when the" other t ermostat is tending to open during each cycle of op-' eratlons.

21'. A heat transfer regulator-for regulating the temperature of a body comprising two thermostats constructed to move to open and closed positions at predetermined temperatures respectively and having different temperature ranges, one thermostat being normally open and the other normally 22. A heat transfer regulator for regulating the temperature of a body comprising two thermostats constructed to move to open and ,closed positions at predetermined temperatures respectively and having different temperature ranges, one thermostat being normally open and the other normally closed, and means conjointly controlled by said thermostats for controlling the temperature of said body.

23. A heat transfer regulator for regulating the temperature of a body comprisin main and auxiliary thermostats constructe to move to open and closed positions, the main thermostat being cupped to snap abruptly from one position to the other to control the temperature .of said body and having a relatively wide temperature range, the auxiliary thermostat having a relatively narrow temperature range and being responsiveto the temperature of'said body, and auxiliary heat transfer means controlled by the auxiliary thermostat independently of the main thermostat for controlling the main thermostat.

'2-1. In a heatinq'system, a main thermostat in heat-transferrelation to the body to be heated and havin means for controlling the temperature of the body, and an auxiliary thermostat in heat-transfer relation to said body and having switch contacts for controlling the temperature of the main thermostat, current through said contacts being controlled by the main thermostat so 12 that current through the contacts is discontinued by the main thermostat and the discontinuity is maintained until after the auxiliary contacts have been separated by the auxiliary thermostatdn each cycle of opera- Cal tion, whereby no arcing can occur at the auxiliary contacts and the auxiliary thermostat and contacts may therefore be constructed more delicately.

25. A thermostatically controlled system comprising main and auxiliary thermostats, switching means controlled by each, and means operatively connecting the two ther mostats whereby the auxiliary switch never opens a live circuit althoughcontrolling the main thermostat.

26. A unitary thermostatic controlling device comprising two thermostats, heating means located near both thermostats and controlled by one thermostat for operating the other thermostat, said heating means keeping the controllingthermostat firmly in its position.

27. A unitary thermostatic controlling device comprising a main thermostat adapted to control the energy supplied to a body, an auxiliary thermostat and auxiliary heater in heat transfer relation to said main thermostat and said body, said auxiliary thermostat controlling the auxiliary heater, which in turn controls the main thermostat, said auxiliary heater, after being energized by said auxiliary thermostat serving to maintain said auxiliary thermostat in its position until the main thermostat operates.

28. A unitary thermostatic controlling de Vice comprising a main thermostat adapted to control the energy supplied to a body, an auxiliary thermostat and heating coil in heat transfer relation to said main thermostat and said body, electrical contacts in the heating coil circuit controlled by said auxiliary thermostat, said heating coil adapted to cause the main thermostat to operate, and to keep the auxiliary thermostat firmly in its energizing position when energized by said auxiliary thermostat.

29. A unitary thermostatic controlling device comprising a main thermostat adapted to control the energy supplied to a body, an auxiliary thermostat and heating coil in heat transfer relation to'said main thermostat and said body, electrical con tacts in the heating coil circuit controlled by said auxiliary thermostat, said auxiliary thermostat adapted to operate at a predetermined higher temperature to close the heating coil circuit, said heating coil adapted to cause the main thermostat to operate and to keep the auxiliary thermostat firmly in its energizing position up to the time said main thermostat operates. y

30. The device of claim 29 wherein the main thermostat controls the energy supplied to said heating coil in addition to the control exercised by the auxiliary thermostat.

31. A unitary thermostatic controlling device comprising a main thermostat adapted to control the energy supplied to a body, an auxiliary thermostat in heat transfer'relation to said body, a heating coil in heat transfer relation to both thermostats, said heating coil being immediately controlled by said auxiliary thermostat and adapted to control the main thermostat, the energy for said heating coil being part of that controlled by the main thermostat, said heating coil thereby maintaining the auxiliary thermostat firmly in energizing position when itself energized.

82. An electric thermostatic switch assembly comprising a main thermostat and auxiliary thermostat, said main thermostat having contacts and controlling an electric circuit, said auxiliary thermostat having contacts, a heating coil deriving energy from said electric circuit and in heat transfer relation to both thermostats, said auxiliary thermostat contacts controlling the heating coil circuit, said auxiliary thermostat closing 5 the heating coil circuit at a predetermined temperature and energizing it, whereupon said heating coil tends to maintain said anxiliary thermostat in its energizing position while tending to cause said main thermostat to operate.

33. An electric thermostatic switch assembly comprising a main thermostat controlling an electric circuit, a heating coil bridged cross part of said circuit and when energized adapted to control the main thermostat, an auxiliary thermostat controlling the heating coil circuit and adapted to close the healing coil circuit at a predetermined tempcratlnre, said heating coil being in heat transfer relation to said auxiliary thermosl at and adapted to maintain it inits energizing position.

Signed by me at Cambridge, Mass, this 20th day of November, 1923.

LAURENCE K. MARSHALL.

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